1. Field of the Invention
The present invention relates to novel compounds having retinoid-like biological activity. More specifically, the present invention relates to amides formed between aryl or heteroryl amines and tetrahydronaphthalene, chroman, thiochroman and 1,2,3,4-tetrahydroquinoline carboxylic acids where at least one of the aromatic or heteroaromatic moieties of the amide bears an electron withdrawing substituent. The compounds are agonists of RAR retinoid receptors.
2. Background Art
Compounds which have retinoid-like activity are well known in the art, and are described in numerous United States and other patents and in scientific publications. It is generally known and accepted in the art that retinoid-like activity is useful for treating animals of the mammalian species, including humans, for curing or alleviating the symptoms and conditions of numerous diseases and conditions. In other words, it is generally accepted in the art that pharmaceutical compositions having a retinoid-like compound or compounds as the active ingredient are useful as regulators of cell proliferation and differentiation, and particularly as agents for treating skin-related diseases, including, actinic keratoses, arsenic keratoses, inflammatory and non-inflammatory acne, psoriasis, ichthyoses and other keratinization and hyperproliferative disorders of the skin, eczema, atopic dermatitis, Darriers disease, lichen planus, prevention and reversal of glucocorticoid damage (steroid atrophy), as a topical anti-microbial, as skin anti-pigmentation agents and to treat and reverse the effects of age and photo damage to the skin. Retinoid compounds are also useful for the prevention and treatment of cancerous and precancerous conditions, including, premalignant and malignant hyperproliferative diseases such as cancers of the breast, skin, prostate, cervix, uterus, colon, bladder, esophagus, stomach, lung, larynx, oral cavity, blood and lymphatic system, metaplasias, dysplasias, neoplasias, leukoplakias and papillomas of the mucous membranes and in the treatment of Kaposi""s sarcoma. In addition, retinoid compounds can be used as agents to treat diseases of the eye, including, without limitation, proliferative vitreoretinopathy (PVR), retinal detachment, dry eye and other corneopathies, as well as in the treatment and prevention of various cardiovascular diseases, including, without limitation, diseases associated with lipid metabolism such as dyslipidemias, prevention of post-angioplasty restenosis and as an agent to increase the level of circulating tissue plasminogen activator (TPA). Other uses for retinoid compounds include the prevention and treatment of conditions and diseases associated with human papilloma virus (HPV), including warts and genital warts, various inflammatory diseases such as pulmonary fibrosis, ileitis, colitis and Krohn""s disease, neurodegenerative diseases such as Alzheimer""s disease, Parkinson""s disease and stroke, improper pituitary function, including insufficient production of growth hormone, modulation of apoptosis, including both the induction of apoptosis and inhibition of T-Cell activated apoptosis, restoration of hair growth, including combination therapies with the present compounds and other agents such as MinoxidilR, diseases associated with the immune system, including use of the present compounds as immunosuppressants and immunostimulants, modulation of organ transplant rejection and facilitation of wound healing, including modulation of chelosis.
U.S. Pat. No. 4,740,519 (Shroot et al.), U.S. Pat. No. 4,826,969 (Maignan et al.), U.S. Pat. No. 4,326,055 (Loeliger et al.), U.S. Pat. No. 5,130,335 (Chandraratna et al.), U.S. Pat. No. 5,037,825 (Klaus et al.), U.S. Pat. No. 5,231,113 (Chandraratna et al.), U.S. Pat. No. 5,324,840 (Chandraratna), U.S. Pat. No. 5,344,959 (Chandraratna), U.S. Pat. No. 5,324,335 (Chandraratna), Published European Patent Application Nos. 0 170 105 (Shudo), 0 176 034 A (Wuest et al.), 0 350 846 A (Klaus et al.), 0 176 032 A (Frickel et al.), 0 176 033 A (Frickel et al.), 0 253 302 A (Klaus et al.), 0 303 915 A (Bryce et al.), UK Patent Application GB 2190378 A (Klaus et al.), German Patent Application Nos. DE 3715955 Al (Klaus et al.), DE 602473 A1 (Wuest et al., and the articles J. Amer. Acad. Derm. 15: 756-764 (1986) (Sporn et al.), Chem. Pharm. Bull. 33: 404-407 (1985) (Shudo et al.), J. Med Chem. 1988 31, 2182-2192 (Kagechika et al.), Chemistry and Biology of Synthetic Retinoids CRC Press Inc. 1990 p 334-335, 354 (Dawson et al.), describe or relate to compounds which include a tetrahydronaphthyl moiety and have retinoid-like or related biological activity. U.S. Pat. No. 4,391,731 (Boller et al.) describes tetrahydronaphthalene derivatives which are useful in liquid crystal compositions.
U.S. Pat. Nos. 4,980,369, 5,006,550, 5,015,658, 5,045,551, 5,089,509, 5,134,159, 5,162,546, 5,234,926, 5,248,777, 5,264,578, 5,272,156, 5,278,318, 5,324,744, 5,346,895, 5,346,915, 5,348,972, 5,348,975, 5,380,877, 5,399,561, 5,407,937, (assigned to the same assignee as the present application) and patents and publications cited therein, describe or relate to chroman, thiochroman and 1,2,3,4-tetrahydroquinoline derivatives which have retinoid-like biological activity. Still further, several co-pending applications and recently issued patents which are assigned to the assignee of the present application, are directed to further compounds having retinoid-like activity.
It is now general knowledge in the art that two main types of retinoid receptors exist in mammals (and other organisms). The two main types or families of receptors respectively designated the RARs and RXRs. Within each type there are subtypes; in the RAR family the subtypes are designated RARxcex1, RARxcex2 and RARxcex93, in RXR the subtypes are: RXRxcex1, RXBxcex2 and RXRxcex93. It has also been established in the art that the distribution of the two main retinoid receptor types, and of the several sub-types is not uniform in the various tissues and organs of mammalian organisms. Accordingly, among compounds having agonist-like activity at retinoid receptors, specificity or selectivity for one of the main types or families, and even specificity or selectivity for one or more subtypes within a family of receptors, is considered a desirable pharmacological property.
The present invention provides compounds having retinoid-like biological activity and specifically compounds which are agonists of one or more RAR retinoid receptor subtypes.
The present invention covers compounds of Formula 
wherein X is S, O, NRxe2x80x2 where Rxe2x80x2 is H or alkyl of 1 to 6 carbons, or
X is [C(R1)2]n where n is an integer between 0 and 2;
R1 is independently H or alkyl of 1 to 6 carbons;
R2 is hydrogen, or lower alkyl of 1 to 6 carbons;
R3 is hydrogen, lower alkyl of 1 to 6 carbons or F;
m is an integer having the value of 0-2;
o is an integer having the value of 0-4;
p is an integer having the value of 0-2;
r is an integer having the value 0-2 with the proviso that when Z is O the sum of p and r is at least 1;
Y is a phenyl or naphthyl group, or heteroaryl selected from a group consisting of pyridyl, thienyl, furyl, pyridazinyl, pyrimidinyl, pyrazinyl, thiazolyl, oxazolyl, imidazolyl and pyrazolyl, said phenyl, naphthyl and heteroaryl groups being optionally substituted with one or two R2 groups;
W is a substituent selected from the group consisting of F, Br, Cl, I, C1-6alkyl, fluoro substituted C1-6 alkyl, NO2, N3, OH, OCH2OCH3, OC1-10alkyl, tetrazol, CN, SO2C1-6-alkyl , SO2C1-6-alkyl, SO2C1-6-fluoro substituted alkyl, SO-C16 alkyl, CO-C1-6alkyl, COOR8, phenyl, phenyl itself substituted with a W group other than with phenyl or substituted phenyl;
L is xe2x80x94(Cxe2x95x90Z)xe2x80x94NHxe2x80x94 or xe2x80x94NHxe2x80x94(Cxe2x95x90Z)xe2x80x94
Z is O or S;
A is (CH2)q where q is 0-5, lower branched chain alkyl having 3-6 carbons, cycloalkyl having 3-6 carbons, alkenyl having 2-6 carbons and 1 or 2 double carbonds, alkynyl having 2-6 carbons and 1 or 2 triple bonds, and
B is COOH or a pharmaceutically acceptable salt thereof, COOR8, CONR9R10, xe2x80x94CH2OH, CH2OR11, CH2 OCOR11, CHO, CH(OR12)2, CHOR13O, xe2x80x94COR7, CR7(OR12)2, CR7OR13O. where R7 is an alkyl, cycloalkyl or alkenyl group containing 1 to 5 carbons, R8 is an alkyl group of 1 to 10 carbons or trimethylsilylalkyl where the alkyl group has 1 to 10 carbons, or a cycloalkyl group of 5 to 10 carbons, or R8 is phenyl or lower alkylphenyl, R9 and R10 independently are hydrogen, an alkyl group of 1 to 10 carbons, or a cycloalkyl group of 5-10 carbons, or phenyl or lower alkylphenyl, R11 is lower alkyl, phenyl or lower alkylphenyl, R12 is lower alkyl, and R13 is divalent alkyl radical of 2-5 carbons.
In a second aspect, this invention relates to the use of the compounds of Formula 1 for the treatment of skin-related diseases, including, without limitation, actinic keratoses, arsenic keratoses, inflammatory and non-inflammatory acne, psoriasis, ichthyoses and other keratinization and hyperproliferative disorders of the skin, eczema, atopic dermatitis, Darriers disease, lichen planus, prevention and reversal of glucocorticoid damage (steroid atrophy), as a topical anti-microbial, as skin anti-pigmentation agents and to treat and reverse the effects of age and photo damage to the skin. The compounds are also useful for the prevention and treatment of cancerous and precancerous conditions, including, premalignant and malignant hyperproliferative diseases such as cancers of the breast, skin, prostate, cervix, uterus, colon, bladder, esophagus, stomach, lung, larynx, oral cavity, blood and lymphatic system, metaplasias, dysplasias, neoplasias, leukoplakias and papillomas of the mucous membranes and in the treatment of Kaposi""s sarcoma. In addition, the present compounds can be used as agents to treat diseases of the eye, including, without limitation, proliferative vitreoretinopathy (PVR), retinal detachment, dry eye and other corneopathies, as well as in the treatment and prevention of various cardiovascular diseases, including, without limitation, diseases associated with lipid metabolism such as dyslipidemias, prevention of post-angioplasty restenosis and as an agent to increase the level of circulating tissue plasminogen activator (TPA). Other uses for the compounds of the present invention include the prevention and treatment of conditions and diseases associated with human papilloma virus (HPV), including warts and genital warts, various inflammatory diseases such as pulmonary fibrosis, ileitis, colitis and
Krohn""s disease, neurodegenerative diseases such as Alzheimer""s disease, Parkinson""s disease and stroke, improper pituitary function, including insufficient production of growth hormone, modulation of apoptosis, including both the induction of apoptosis and inhibition of T-Cell activated apoptosis, restoration of hair growth, including combination therapies with the present compounds and other agents such as MinoxidilR, diseases associated with the immune system, including use of the present compounds as immunosuppressants and immunostimulants, modulation of organ transplant rejection and facilitation of wound healing, including modulation of chelosis.
This invention also relates to a pharmaceutical formulation comprising a compound of Formula 1 in admixture with a pharmaceutically acceptable excipient.
In another aspect, this invention relates to processes for making a compound of Formula 1 which processes comprise reacting, in the presence of an acid acceptor or water acceptor, a compound of Formula 2 with a compound of Formula 3 or a compound of Formula 2a with a compound of Formula 3a where X1 is OH, halogen, or other group which renders the xe2x80x94COX1 group reactive for amide formation, and where the remaining symbols are defined as in connection with Formula 1. 
Still further, the present invention relates to such reactions performed on the compounds of Formula 1 which cause transformations of the B group while the reaction product still remains within the scope of Formula 1.
Definitions
The term alkyl refers to and covers any and all groups which are known as normal alkyl, branched-chain alkyl and cycloalkyl. The term alkenyl refers to and covers normal alkenyl, branch chain alkenyl and cycloalkenyl groups having one or more sites of unsaturation. Similarly, the term alkynyl refers to and covers normal alkynyl, and branch chain alkynyl groups having one or more triple bonds.
Lower alkyl means the above-defined broad definition of alkyl groups having 1 to 6 carbons in case of normal lower alkyl, and as applicable 3 to 6 carbons for lower branch chained and cycloalkyl groups.
Lower alkenyl is defined similarly having 2 to 6 carbons for normal lower alkenyl groups, and 3 to 6 carbons for branch chained and cyclo-lower alkenyl groups. Lower alkynyl is also defined similarly, having 2 to 6 carbons for normal lower alkynyl groups, and 4 to 6 carbons for branch chained lower alkynyl groups.
The term xe2x80x9cesterxe2x80x9d as used here refers to and covers any compound falling within the definition of that term as classically used in organic chemistry. It includes organic and inorganic esters. Where B of Formula 1 is xe2x80x94COOH, this term covers the products derived from treatment of this function with alcohols or thioalcohols preferably with aliphatic alcohols having 1-6 carbons. Where the ester is derived from compounds where B is xe2x80x94CH2OH, this term covers compounds derived from organic acids capable of forming esters including phosphorous based and sulfur based acids, or compounds of the formula xe2x80x94CH2OCOR1, where R11 is any substituted or unsubstituted aliphatic, aromatic, heteroaromatic or aliphatic aromatic group, preferably with 1-6 carbons in the aliphatic portions.
Unless stated otherwise in this application, preferred esters are derived from the saturated aliphatic alcohols or acids of ten or fewer carbon atoms or the cyclic or saturated aliphatic cyclic alcohols and acids of 5 to 10 carbon atoms. Particularly preferred aliphatic esters are those derived from lower alkyl acids and alcohols. Also preferred are the phenyl or lower alkyl phenyl esters.
Amides has the meaning classically accorded that term in organic chemistry. In this instance it includes the unsubstituted amides and all aliphatic and aromatic mono- and di- substituted amides. Unless stated otherwise in this application, preferred amides are the mono- and di-substituted amides derived from the saturated aliphatic radicals of ten or fewer carbon atoms or the cyclic or saturated aliphatic-cyclic radicals of 5 to 10 carbon atoms. Particularly preferred amides are those derived from substituted and unsubstituted lower alkyl amines. Also preferred are mono- and disubstituted amides derived from the substituted and unsubstituted phenyl or lower alkylphenyl amines. Unsubstituted amides are also preferred.
Acetals and ketals include the radicals of the formula-CK where x is (xe2x80x94OR)2. Here, R is lower alkyl. Also, K may be xe2x80x94OR7Oxe2x80x94 where R7 is lower alkyl of 2-5 carbon atoms, straight chain or branched.
A pharmaceutically acceptable salt may be prepared for any compounds in this invention having a functionality capable of forming such-salt, for example an acid functionality. A pharmaceutically acceptable salt is any salt which retains the activity of the parent compound and does not impart any deleterious or untoward effect on the subject to which it is administered and in the context in which it is administered. Pharmaceutically acceptable salts may be derived from organic or inorganic bases. The salt may be a mono or polyvalent ion. Of particular interest are the inorganic ions, sodium, potassium, calcium, and magnesium. Organic salts may be made with amines, particularly ammonium salts such as mono-, di- and trialkyl amines or ethanol amines. Salts may also be formed with caffeine, tromethamine and similar molecules. Where there is a nitrogen sufficiently basic as to be capable of forming acid addition salts, such may be formed with any inorganic or organic acids or alkylating agent such as methyl iodide. Preferred salts are those formed with inorganic acids such as hydrochloric acid, sulfuric acid or phosphoric acid. Any of a number of simple organic acids such as mono-, di- or tri- acid may also be used.
Some of the compounds of the present invention may have trans and cis (E and Z) isomers. In addition, the compounds of the present invention may contain one or more chiral centers and therefore may exist in enantiomeric and diastereomeric forms. The scope of the present invention is intended to cover all such isomers per se, as well as mixtures of cis and trans isomers, mixtures of diastereomers and racemic mixtures of enantiomers (optical isomers) as well.
With reference to the symbol Y in Formula 1, the preferred compounds of the invention are those where Y is phenyl, pyridyl, 2-thiazolyl, thienyl, or furyl, more preferably phenyl. As far as substitutions on the Y (phenyl) and Y (pyridyl) groups are concerned, compounds are preferred where the phenyl group is 1,4 (para) substituted by the L and A-B groups, and where the pyridine ring is 2,5 substituted by the L and A-B groups. (Substitution in the 2,5 positions in the xe2x80x9cpyridinexe2x80x9d nomenclature corresponds to substitution in the 6-position in the xe2x80x9cnicotinic acidxe2x80x9d nomenclature.) In the preferred compounds of the invention there is no optional R2 substituent on the Y group.
As far as the amide or carbamoyl function xe2x80x9cLxe2x80x9d is concerned which links the two cyclic portions of the molecule, L is preferably xe2x80x94CZxe2x80x94NHxe2x80x94; in other words amide or carbamoyl compounds are preferred in accordance with the present invention where the carbonyl (COxe2x80x94) or thiocarbonyl (CSxe2x80x94) group is linked to the condensed cyclic moiety.
With reference to the symbol X in Formula 1, compounds are preferred in accordance with the invention where x is [C(R1)2]. and n is 1, and also where X is C or S (chroman and thiochroman derivatives).
The R1 groups are preferably H or CH3. The R3 group is preferably hydrogen.
The A-B group of the preferred compounds is (CH2)nxe2x80x94COOH or (CH2)nxe2x80x94COOR8, where n and R8 are defined as above. Even more preferably n is zero and R8 is lower alkyl, or n is zero and B is COOH or a pharmaceutically acceptable salt thereof.
Referring now to the W group in Formula 1, this group is, generally speaking, an electron withdrawing group, which is present in the compounds of the invention either in the aromatic portion of the condensed ring system, or as a substituent of the aryl or heteroaryl group Y. Preferably the W group is present in the Y group, or both in the Y group and also in the aromatic portion of the condensed ring system. When the Z group is S (thioamides) a W group does not necessarily have to be present in the compounds of the invention, although preferably at least one W group is nevertheless present. In the aryl or heteroaryl Y moiety the W group is preferably located in the position adjacent to the A-B group; preferably the A-B group is in para position in the phenyl ring relative to the xe2x80x9camidexe2x80x9d moiety, and therefore the W group is preferably in meta position relative to the amide moiety. Where the W group is also present in the aromatic portion of the condensed ring system, it preferably occupies the 8 position of the chroman or thiochroman nucleus with the Zxe2x95x90Cxe2x80x94NHxe2x80x94 group occupying the 6 position. In tetrahydronaphthalene compounds of the invention the Zxe2x95x90Cxe2x80x94NHxe2x80x94 group is preferably in the 2-position, and the W group is in the 3 or 4 position. Preferred W groups are F, NO2, Br, I, CF3, N3, and OH. The presence of one or two fluoro substituents in the Y group is especially preferred. When the Y group is phenyl, the fluoro substituents preferably are in the ortho and orthoxe2x80x2 positions relative to the A-B group, which is preferably COOH or COOR8.
The most preferred compounds of the invention are shown in Table 1, with reference to Formulas 4 and 5. 
The compounds of this invention may be administered systemically or topically, depending on such considerations as the condition to be treated, need for site-specific treatment, quantity of drug to be administered, and numerous other considerations.
In the treatment of dermatoses, it will generally be preferred to administer the drug topically, though in certain cases such as treatment of severe cystic acne or psoriasis, oral administration may also be used. Any common topical formulation such as a solution, suspension, gel, ointment, or salve and the like may be used. Preparation of such topical formulations are well described in the art of pharmaceutical formulations as exemplified, for example, Remington""s Pharmaceutical Science, Edition 17. Mack Publishing Company, Easton, Pennsylvania. For topical application, these compounds could also be administered as a powder or spray, particularly in aerosol form. If the drug is to be administered systemically, it may be confected as a powder, pill, tablet or the like or as a syrup or elixir suitable for oral administration. For intravenous or intraperitoneal administration, the compound will be prepared as a solution or suspension capable of being administered by injection. In certain cases, it may be useful to formulate these compounds by injection. In certain cases, it may be useful to formulate these compounds in suppository form or as extended release formulation for deposit under the skin or intramuscular injection.
Other medicaments can be added to such topical formulation for such secondary purposes as treating skin dryness; providing protection against light; other medications for treating dermatoses; medicaments for L:preventing infection, reducing irritation, inflammation and the like.
Treatment of dermatoses or any other indications known or discovered to be susceptible to treatment by retinoic acid-like compounds will be effected by administration of the therapeutically effective dose of one or more compounds of the instant invention. A therapeutic concentration will be that concentration which effects reduction of the particular condition, or retards it expansion. In certain instances, the compound potentially may be used in prophylactic manner to prevent onset of a particular condition.
A useful therapeutic or prophylactic concentration will vary from condition to condition and in certain instances may vary with the severity of the condition being treated and the patient""s susceptibility to treatment. Accordingly, no single concentration will be uniformly useful, but will require modification depending on the particularities of the disease being treated. Such concentrations can be arrived at through routine experimentation. However, it is anticipated that in the treatment of, for example, acne, or similar dermatoses, that a formulation containing between 0.01 and 1.0 milligrams per mililiter of formulation will constitute a therapeutically effective concentration for total application. If administered systemically, an amount between 0.01 and 5 mg per kg per day of body eight would be expected to effect a therapeutic result in the treatment of many disease for which these compounds are useful.
The retinoid-like activity of the compounds of the invention can be confirmed in assays wherein ability of the compound to bind to retinoid receptors is measured. As it is noted in the introductory section of this application for patent two main types of retinoic acid receptors (RAR and RXR) exist in mammals (and other organisms). Within each type there are sub-types (RARxcex1, RARxcex2, RARxcex93, RXRxcex1, RXRxcex2 and RXRxcex93) the distribution of which is not uniform in the various tissues and organs of mammalian organisms. Selective binding of only one or two retinoid receptor subtypes within one retinoid receptor family can give rise to beneficial pharmacological properties because of the varying distribution of the sub-types in the several mammalian tissues or organs. For the above-summarized reasons, binding of any or all of the retinoid receptors, as well as specific or selective activity in a receptor family, or selective or specific activity in any one of the receptor subtypes, are all considered desirable pharmacological properties.
In light of the foregoing the prior art has developed assay procedures for testing the agonist like activity of compounds in the RARxcex1, RARxcex2 RARxcex93, RXRxcex1, RXRxcex2 and RXRxcex93 receptor subtypes. For example, a chimeric receptor transactivation assay which tests for agonist-like activity in the RARxcex1, RARxcex2, RARxcex93, and RXRxcex1 receptor subtypes, and which is based on work published by Feigner P. L. and Holm M. (1989) Focus, 11 2 is described in detail in U.S. Pat. No. 5,455,265. The specification of U.S. Pat. No. 5,455,265 is expressly incorporated herein by reference.
A holoreceptor transactivation assay and a ligand binding assay which measure the ability of the compounds of the invention to bind to the several retinoid receptor subtypes, respectively, are described in published PCT Application No. WO WO93/11755 (particularly on pages 30-33 and 37-41) published on Jun. 24, 1993, the specification of which is also incorporated herein by reference. A description of the ligand binding assay is also provided below.
BINDING ASSAY
All binding assays were performed in a similar fashion. All six receptor types were derived from the expressed receptor type (RAR xcex1, xcex2, xcfx84 and RXR xcex1, xcex2, xcfx84) expressed in Baculovirus. Stock solutions of all compounds were prepared as 10 mM ethanol solutions and serial dilutions carried out into 1:1 DMSO; ethanol. Assay buffers consisted of the following for all six receptor assays: 8% glycerol, 120 mM KCl, 8 mM Tris, 5 mM CHAPS 4 mM DTT and 0.24 mM PMSF, pH-7.4@room temperature.
All receptor biding assays were performed in the same manner. The final assay volume was 250 xcexcl and contained from 10-40 g of extract protein depending on receptor being assayed along with 5 nM of [3H) alltrans retinoic acid or 10 nM [3H) 9-cis retinoic acid and varying concentrations of competing ligand at concentrations that ranged from 0-10xe2x88x925 M. The assays were formatted for a 96 well minitube system. Incubations were carried out at 4xc2x0 C. until equilibrium was achieved. Non-specific binding was defined as that binding remaining in the presence of 1000 nM of the appropriate unlabeled retinoic acid isomer. At the end of the incubation period, 50 xcexcl of 6.25% hydroxyapitite was added in the appropriate wash buffer. The wash buffer consisted of 100 mM KCl, 10 mM Tris and either 5 mM CHAPS (RXR xcex1, xcex2, xcfx84) or 0.5% Triton X-100 (RAR xcex1, xcex2, xcfx84). The mixture was vortexed and incubated for 10 minutes at 4xc2x0 C., centrifuged and the supernatant removed. The hydroxyapitite was washed three more times with the appropriate wash buffer. The receptor-ligand complex was adsorbed by the hydroxyapitite. The amount of receptor-ligand complex was determined by liquid scintillation counting of hydroxyapitite pellet.
After correcting for non-specific binding, IC50 values were determined. The IC50 value is defined as the concentration of competing ligand needed to reduce specific binding by 50%. The IC50 value was determined graphically from a loglogit plot of the data. The Kd values were determined by application of the ChengPrussof equation to the IC50 values, the labeled ligand concentration and the Kd of the labeled ligand.
The results of ligand binding assay are expressed in Kd numbers. (See Cheng et al. Biochemical Pharmacology Vol. 22 pp 3099-3108, expressly incorporated herein by reference.)
Table 2 shows the results of the ligand binding assay for certain exemplary compounds of the invention.
As it can be seen from the test results summarized in Table 2, the therein indicated exemplary compounds of the invention bind specifically or selectively to RARxcex1 receptors.
CANCER CELL LINE ASSAYS
Hormones
All trans-Retinoic acid (t-RA) (Sigma Chemicals Co., St. Louis, M.) was stored at xe2x88x9270xc2x0 C. Prior to each experimet the compound was dissolved in 100% ethanol at 1 mM and diluted in culture medium immediately before use. All experiments were performed in subdued light. Controls were assayed using the same concentration of ethanol as present in the experimental plates and this concentration of diluent had no effect in either assay.
Cells and Cell Culture
All cell lines, RPMI 8226, ME-180 and AML-193 were obtained from the American Type Culture Collection (ATCC, Rockville, Md.). RPMI 8226 is a human hematopoietic cell line obtained from the peripheral blood of a patient with multiple myeloma. The cells resemble the lymphoblastoid cells of other human lymphocyte cell lines and secrete xcex1-type light chains of immunoglobulin. RPMI-8226 cells are grown in RPMI medium (Gibco) supplemented with 10% fetal bovine serum, glutamine and antibiotics. The cells were maintained as suspension cultures grown at 37xc2x0 C. in a humidified atmosphere of 5% CO2 in air. The cells were diluted to a concentration of 1xc3x97105/ml twice a week.
ME-180 is a human epidermoid carcinoma cell line derived from the cervix. The tumor was a highly invasive squamous cell carcinoma with irregular cell clusters and no significant keratinization. ME-180 cells were grown and maintained in McCoy""s 5a medium (Gibco) supplemented with 10% fetal bovine serum, glutamine and antibiotics. The cells were maintained as monolayer cultures grown at 37xc2x0 C. in a humidified atmosphere of 5% CO2 in air. The cells were diluted to a concentration of 1xc3x97105/ml twice a week.
AML-193 was established from the blast cells classified as M5 Acute Monocyte Leukemia. The growth factor, granulocyte colony-stimulation factor (GM-CSF) was required to establish this cell line and growth factors are necessary for its continuous proliferation in chemically defined medium. AML-193 cells were grown and maintained in Iscove""s modified Dulbeccous medium supplemented with 10% fetal bovine serum, glutamine and antibiotics with 5 xcexcg/ml insulin (Sigma Chemical Co.) and 2 ng/ml rh GM-CSF (R and D Systems). The cells were diluted to a concentration of 3xc3x97105/ml twice a week.
Incorporation of 3H-Thymidine
The method used for determination of the incorporation of radiolabeled thymidine was adapted from the procedure described by Shrivastav et al. RPMI-8226 cells were plated in a 96 well round bottom microtiter plate (Costar) at a density of 1,000 cells/well. To appropriate wells, retinoid test compounds were added at the final concentrations indicated for a final volume of 150 xcexcl/well. The plates were incubated for 96 hours at 37xc2x0 C. in a humidified atmosphere of 5% CO2 in air. Subsequently, 1 xcexcCi of (5xe2x80x2-3H]-thymidine (Amersham, U.K. 43 Ci/mmol specific activity) in 25 xcexcl culture medium was added to each well and the cells were incubated for an additional 6 hours. The cultures were further processed as described below.
ME-180 wells, harvested by trypsinization were plated in a 96 well flat bottom microtiter plate (Costar) at a density of 2,000 cells/well. The cultures were treated as described above for RPMI 8226 with the following exceptions. After incubation with thymidine the supernatant was carefully removed, and the cells were washed with a 0.5 mM solution of thymidine in phosphate buffered saline. ME180 cells were briefly treated with 50 xcexcl of 2.5% trypsin to dislodge the cells from the plate. AML-193 cells were plated in a 96 well round bottom microtiter plate (Costar) at a density of 1,000 cells/well. To appropriate wells, retinoid test compounds were added at the final concentrations indicated for a final volume of 150 xcexcl/well. The plates were incubated for 96 hours at 37xc2x0 C. in a humidified atmosphere of 5% CO2 in air. Subsequently, 1 xcexcCi of [5xe2x80x2-3H]-thymidine (Amersham, U.K., 43 Ci/mmol specific activity) in 25 xcexcl culture medium was added to each well and the cells were incubated for an additional 6 hours.
All cells lines were then processed as follows: the cellular DNA was precipitated with lot trichloroacetic acid onto glass fiber filter mats using a SKATRON multi-well cell harvester (Skatron Instruments, Sterling Va.). Radioactivity incorporated into DNA, as a direct measurement of cell growth, was measured by liquid scintillation counting. The numbers represent the mean disintegrations per minute of incorporated thymidine from triplicate wellsxc2x1SEM.
In the above noted in vitro cell lines exemplary compounds 6, 8, 12, 14 and 20 of the invention caused significant decrease in the proliferation of the tumor cell lines (as measured by incorporation of radioactive labeled thymidine) in the 10xe2x88x9211 to 10xe2x88x926 molar concentration range of the respective test compound.
The compounds of this invention can be made by the synthetic chemical pathways illustrated here. The synthetic chemist will readily appreciate that the conditions set out here are specific embodiments which can be generalized to any and all of the compounds represented by Formula 1.
Generally speaking the process of preparing compounds of the invention involves the formation of an amide by the reaction of a compound of the general Formula 2 with a compound of general Formula 3, or by the reaction of a compound of general Formula 2a with a compound of general Formula 3a as these formulas are defined in the Summary section of the present application for patent. Thus, as is noted above, a compound of Formula 2 is an acid or an xe2x80x9cactivated formxe2x80x9d of a carboxylic acid attached to the aromatic portion of a tetrahydronaphthalene, (Z=[C(R1)2]n and n is 1), dihydroindene ([C(R1)2]n where n is 0), chroman (Z is O), thiochroman (X is S), or tetrahydroquinoline (X is NRxe2x80x2) nucleus. The carboxylic acid, or its xe2x80x9cactivated formxe2x80x9d is attached to the 2 or 3 position of the tetrahyronaphthalene, and to the 6 or 7 position of the chroman, thiochroman or tetrahydroquinoline moieties. In the preferred compounds of the invention the attachment is to the 2 position of tetrahydronaphthalene and to the 6 position of chroman, thiochroman or tetrahydroquinoline.
The term xe2x80x9cactivated formxe2x80x9d of the carboxylic acid should be understood in this regard as such derivative of the carboxylic acid which is capable of forming an amide when reacted with a primary amine of Formula 3. In case of the xe2x80x9creverse amidesxe2x80x9d the activated form of a carboxylic acid is a derivative (Formula 3a) that is capable of forming an amide when reacted with a primary amine of Formula 2a. This, generally speaking, means such derivatives of a carboxylic acid which are normally known and used in the art to form amide linkages with an amine. Examples of suitable forms or derivatives for this purpose are acid chlorides, acid bromides, and esters of the carboxylic acid, particularly active esters, where the alcohol moiety of the ester forms a good leaving group. Presently most referred as reagents in accordance with Formula 2 (or Formula 3a) are acid chlorides (x1 is Cl). The acid chlorides of Formula 2 (or of Formula 3a) can be prepared by traditional methods from the corresponding esters (X1 is for example ethyl) by hydrolysis and treatement with thionyl chloride (SOCl2). The acid chlorides of Formula 2 (or of Formula 3a) can also be prepared by direct treatment of the carboxylic acids with thionyl chloride, where the carboxylic acid, rather than an ester thereof is available commercially or by a known synthetic procedure. The acid chlorides of Formula 2 (or of Formula 3a) are typically reacted with the amine of Formula 3 (or amine of Formula 2a) in an inert solvent, such as methylene chloride, in the presence of an acid acceptor, such as pyridine.
The carboxylic acids themselves in accordance with Formula 2 (or Formula 3a) are also suitable for amide formation when reacted with an amine, a catalyst (4-dimethylaminopyridine) in the presence of a dehydrating agent, such as dicyclohexylcarbodiimide (DCC) or more pereferably 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC).
The carboxylic acids or the corresponding esters of Formula 2, are generally speaking, prepared as described in the chemical scientific or patent literature and the literature procedures for their preparation may be modified, if necessary, by such chemical reactions or processes which per se are known in the art. For example, generally speaking, 2,2, 4,4 and/or 2,2,4,4-substituted chroman 6-carboxylic acids and chroman 7-carboxylic acids are available in accordance with the teachings of U.S. Pat. Nos. 5,006,550, 5,314,159, 5,324,744, and 5,348,975, the specifications of which are expressly incorporated herein by reference. 2,2, 4,4 and/or 2,2,4,4-substituted thiochroman 6-carboxylic acids are available in accordance with the teachings of U.S. Pat. No. 5,015,658, the specifications of which is expressly incorporated herein by reference. 5,6,7,8-Tetrahydronaphthalene-2-carboxylic acids are, generally speaking, available in accordance with the teachings of U.S. Pat. No. 5,130,335, the specifications of which is expressly incorporated herein by reference. 
Reaction Schemes 1 and 2 provide examples for the synthesis of derivatives of 5,6,7,8-tetrahydro-5,5,8,8-tetramethylnaphthalene-2-carboxylic acid, which are within the scope of Formula 2 and which are reacted with an amine of Formula 3 to provide (5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-naphthalene-2-yl)carbamoyl derivatives within the scope of Formula 1. Thus, as is shown in Reaction Scheme 1, ethyl 5,6,7,8-tetrahydro-5,5,8,8-tetramethylnaphthalene-2-carboxylate (Compound A) is nitrated to provide the corresponding 3-nitro compound (Compound B). The nitro group of Compound B is reduced to provide the corresponding 3-amino compound (Compound C) which is described in the publication Lehmann et al. Cancer Research, 1991, 51, 4804. Ethyl 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-3-aminonaphthalene-2-carboxylate (Compound C) is brominated to yield the corresponding 4-bromo derivative (Compound D), which is converted by treatment with isoamylnitrite and reduction with H3PO2, to ethyl 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-4-bromonaphthalene-2-carboxylate (Compound E). Saponification of Compound E yields 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-4-bromonaphthalene-2-carboxylic acid (Compound F) which is used as a reagent in accordance with Formula 2. Ethyl 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-3-aminonaphthalene-2-carboxylate (Compound C) is also diazotized and reacted with HBF4 to provide ethyl 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-3-fluoronaphthalene-2-carboxylate (Compound G) which serves either per se or after saponification as a reagent in accordance with Formula 2.
5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-hydroxynaphthalene (Compound H, available in accordance with the publication Krause Synthesis 1972 140), is the starting material in the example shown in Reaction Scheme 2. Compound H is brominated to provide the corresponding 3-bromo compound (Compound I) which is thereafter protected in the hydroxyl function by treatment with methoxymethyl chloride (MOMCl) to yield 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-3-methoxymethoxy-2-bromonaphthalene (Compound J). Compound J is reacted with t-butyllithium and carbon dioxide to provide the corresponding carboxylic acid (Compound K) from which the methoxymethyl protecting group is removed by acid to give 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-hydroxynaphthalene-3-carboxylic acid (Compound L). Compound L is brominated to yield 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-1-bromo-2-hydroxynaphthalene-3-carboxylic acid (Compound M). Compound L and Compound M serve as reagents in accordance with Formula 2. The hydroxy group of Compound M is protected for further transformations with methoxymethyl chloride (MOMCl) in the presence of base, yielding 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-1-bromo-2-methoxymethoxynaphthalene-3-carboxylic acid (Compound N). 
Reaction Schemes 3, 4 and 5 provide examples for the synthesis of derivatives of 2,2,4,4 and 4,4-substituted chroman-6-carboxylic acids which can serve as reagents in accordance with Formula 2 for the synthesis of the carbamoyl (amide) compounds within the scope of the present invention. Thus, referring now to Reaction Scheme 3, 2,2,4,4-tetramethylchroman-6-carboxylic acid (Compound O. see U.S. Pat. No. 5,006,550) is brominated with bromine in acetic acid to yield the corresponding 8-bromo derivative (Compound P). Compound P is converted to the acid chloride by treatment with thionyl chloride, and the resulting acid chloride is suitable for reaction with an amine of Formula 3 to provide the carbamoyl (amide) compounds of the invention. The acid chloride is also reacted with an alcohol (methanol) in the presence of base to yield the corresponding ester, methyl 2,2,4,4-tetramethyl-8-bromochroman-6-carboxylate (Compound R). The bromo function of Compound R is converted to a trifluoromethyl function by treatment with sodium trifluoroacetate in the presence of cuprous iodide catalyst and 1-methyl-2-pyrrolidinone (NMP), and the carboxylate ester group is saponified to yield 2,2,4,4-tetramethyl-8-trifluoromethylchroman-6-carboxylic acid (Compound S). Compound B is within the scope of Formula 2 and is suitable per se or as the acid chloride or in other xe2x80x9cactivatedxe2x80x9d form to react with the amines of Formula 3 to yield the carbamoyl (amide) compounds of the invention. 2,2,4,4-Tetramethylchroman-6-carboxylic acid (Compound 0) is also converted to the methyl ester (Compound T) which is then nitrated to yield 2,2,4,4-tetramethyl-8-nitrochroman-6-carboxylic acid (Compound V), still another reagent within the scope of Formula 2. Moreover, in the example further shown in Reaction Scheme 3, 2,2,4,4-tetramethylchroman-6-carboxylic acid (Compound O) is converted to the ethyl ester and nitrated thereafter to yield ethyl 2,2,4,4-tetramethyl-8-nitrochroman-6-carboxylate (Compound W). Still further, Compound O is reacted with ICl to yield 2,2,4,4-tetramethyl-8-iodochroman-6-carboxylic acid (Compound X).
In accordance with the example shown in Reaction Scheme 4, 2-methylphenol is subjected to a series of reactions in accordance with the teachings of U.S. Pat. No. 5,045,551 (incorporated herein by reference) to yield 2,2,4,4,8-pentamethylchroman (Compound Y). Compound Y is brominated with bromine in acetic acid to give 2,2,4,4,8-pentamethyl-6-bromochroman (Compound Z) which is reacted with t-butyl lithium and thereafter with carbon dioxide to give 2,2,4,4,8-pentamethylchroman-6-carboxylic acid (Compound A1).
Reaction Scheme 5 illustrates the synthesis of 4,4-dimethyl-8-bromochroman-6-carboxylic acid (Compound B1) by bromination of 4,4,-dimethyl-chroman-6-carboxylic acid which is available in accordance with the teachings of U.S. Pat. No. 5,059,621, the specification of which is incorporated herein by reference. 2,2,4,4,8-Pentamethylchroman-6-carboxylic acid (Compound Al) and 4,4,-dimethyl-8-bromochroman-6-carboxylic acid (Compound B1) serve as reagents, either per se, or as the corresponding acid chlorides (or other xe2x80x9cactivated form), in accordance with Formula 2 for the synthesis of the carbamoyl (amide) compounds of the present invention.
Referring back now to the reaction between the reagent of Formula 2 with an amine compound of Formula 3 it is noted that the amine compounds are, generally speaking, available in accordance with the state-of-the-art. as described in the scientific and patent literature. More specifically, the amine compounds of Formula 3 can be prepared as described in the scientific and patent literature, or from known compounds of the literature, by such chemical reactions or transformations which are within the skill of the practicing organic chemist. Reaction Scheme 6 illustrates examples for the preparation of amine compounds of Formula 3 (where Y is phenyl) from commercially available starting materials (Aldrich Chemical Company, or Research Plus, Inc. The illustrated compounds of Formula 3 are used for the synthesis of several preferred compounds of the invention. 
Thus, in accordance with Reaction Scheme 6, 3-nitro-6-methyl-fluorobenzene (Aldrich) is subjected to oxidation, conversion of the resulting carboxylic acid to an acid chloride and thereafter to an ethyl ester, followed by reduction of the nitro group, to yield ethyl 2-fluoro-4-amino-benzoate (Compound C1). 3-Nitro-6-methyl-bromobenzene (Aldrich) and 3-nitro-6-methyl-chlorobenzene (Aldrich) are subjected to essentially to the same series of reactions to yield ethyl 2-bromo-4-amino-benzoate (Compound D1) and ethyl 2-chloro-4-amino-benzoate (Compound E1), respectively. 2-Nitro-4-aminobenzoic acid (Research Plus) is converted to its methyl ester (Compound F1) through the corresponding acid chloride. 2,3,5,6-Tetrafluoro-4-amino-benzoic acid (Aldrich) is esterified by treatment with ethanol in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine in CH2Cl2 to give ethyl 2,3,5,6-tetrafluoro-4-amino-benzoate (Compound G1). 2,4,6-Trifluorobenzoic acid (Aldrich) is converted to the methyl ester through the acid chloride, and the 4-fluoro atom is displaced by reaction with sodium azide, followed by hydrogenation, to yield methyl 2,6-difluoro-4-amino benzoate (Compound H1). Compounds C1, D1, E1, F1, G1 and H1 serve as amine reagents in accordance with Formula 3. Further examples of reagents in accordance with Formula 3 are nitro, fluoro, chloro, bromo and trifluoromethyl derivatives of amino substituted heteroaryl carboxylic acids, or their lower alkyl esters, such as ethyl 2-amino-4-chloropyridine 2-carboxylate, ethyl 5-amino-3-chloropyridine 5-carboxylate, and 3,4-dibromo-5-aminothiophene-2-carboxylic acid. The latter examples can be prepared by respective chlorination or bromination of 2-aminopyridine-5-carboxylic acid or of its ester, 3-aminopyridine-6-carboxylic acid or of its ester (described in WO 93/06086) and of 2-aminothiophene-5-carboxylic acid (described in PCT/US92/06485).
The reaction between the compounds of Formula 2 and Formula 3 or between compounds of Formula 2a and 3a, described above, comprises the actual synthesis of the carbamoyl (amide) compounds of the invention. Numerous examples of this reaction are described in detail in the experimental section below. The carbamoyl (amide) compounds of the invention can be converted into thiocarbamoyl (thioamide) compounds of the invention where with reference to Formula 1 Z is S, by reacting the carbamoyl (amide) compound with 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide (Lawesson""s reagent). This reaction is illustrated in Reaction Scheme 7 for two specific examples for the compounds of the invention. 
In Reaction Scheme 7 one starting material ethyl 4-[5xe2x80x2,6xe2x80x2,7xe2x80x2,8xe2x80x2-tetrahydro-5xe2x80x2,5xe2x80x2,8xe2x80x2,8xe2x80x2-tetramethylnaphthalen-2-yl)carbamoyl]benzoate (Compound I1) is obtained in accordance with the teachings of Kagechika et al. J. Med Chem. 1988 31, 2182-2192. The other starting material, ethyl 2-fluoro-4-[5xe2x80x2,6xe2x80x2,7xe2x80x2,8xe2x80x2-tetrahydro-5xe2x80x2,5xe2x80x2,8xe2x80x2,8xe2x80x2-tetramethylnaphthalen-2-yl)carbamoyl]benzoate (Compound 1) is obtained in accordance with the present invention. 
Reaction schemes 8, 9 and 10 disclose examples for the preparation of carbamoyl (amide) compounds of the invention, first by a coupling reaction of a compound of Formula 2 with a compound of Formula 3, followed by one or more reactions performed on the carbamoyl (amide) compound that has been first obtained directly in the coupling reaction. Thus, as is shown in Reaction Scheme 8, 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-3-methoxymethoxynaphthalene-2-carboxylic acid (Compound K) is coupled with ethyl 4-amino-2-fluorobenzoate (Compound C1) in CH2Cl2 in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and dimethylaminopyridine (DMAP) to give ethyl 2-fluoro-4-[5xe2x80x2,6xe2x80x2,7xe2x80x2,8xe2x80x2-tetrahydro-5xe2x80x2,5xe2x80x2,8xe2x80x2,8xe2x80x2-tetramethyl-2xe2x80x2-methoxymethoxy-naphthalen-3xe2x80x2-yl)carbamoyl]benzoate (Compound K1). The methoxymethyl protecting group is removed from Compound K1 by treatment with thiophenol and borontrifluoride ethereate resulting in ethyl 2-fluoro-4-[5xe2x80x2,6xe2x80x2,7xe2x80x2,8xe2x80x2-tetrahydro-5xe2x80x2,5xe2x80x2,8xe2x80x2,8xe2x80x2-tetramethyl-2xe2x80x2-hydroxy-naphthalen-3xe2x80x2-yl)carbamoyl]-benzoate (Compound 7). The hydroxy function of Compound 7 is converted into an n-hexyl ether by treatment with hexyl iodide in the presence of mild base.
In accordance with Reaction Scheme 9 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-1-bromo-2-methoxymethoxynaphthalene-3-carboxylic acid (Compound N) is coupled with methyl 4-amino-2,6-difluorobenzoate (Compound H1) in CH2Cl2 solvent in the presence of ethylcarbodiimide hydrochloride (EDC) and DMAP to provide methyl 2,6-difluoro-4-[(5xe2x80x2,6xe2x80x2,7xe2x80x2,8xe2x80x2-tetrahydro-5xe2x80x2,5xe2x80x2,8xe2x80x2,8xe2x80x2-tetramethyl-1xe2x80x2-bromo-2xe2x80x2-methoxymethoxynaphthalen-3xe2x80x2-yl)carbamoyl]benzoate (Compound M1), from which the esterifying methyl group and the methoxymethyl protecting group are removed by treatement with base and acid, respectively.
Reaction Scheme 10 discloses the example of converting 2,2,4,4-tetramethyl-8-nitrochroman-6-carboxylic acid (Compound V) into the corresponding acid chloride by treatment with thionyl chloride, followed by coupling with ethyl 4-amino-2-fluorobenzoate (Compound C1) and hydrogenation to yield ethyl 2-fluoro-4-[(2xe2x80x2,2xe2x80x2,4xe2x80x2,4xe2x80x2-tetramethyl-8xe2x80x2-amino-6xe2x80x2-chromanyl)carbamoyl]benzoate (Compound N1). Compound N1 is converted to the corresponding 8-azido compound, ethyl 2-fluoro-4-[(2xe2x80x2,2xe2x80x2,4xe2x80x2,4xe2x80x2-tetramethyl-8xe2x80x2-azido-6xe2x80x2-chromanyl)carbamoy]abenzoate (Compound 15) by treatment of isoamyl nitrate and NaN3. 
Reaction Scheme 11 illustrates the synthesis of the primary amine compounds of Formula 2a from the acid chlorides (X1=Cl) or other form of activated acids of Formula 2 where the primary amine of Formula 2a is not available by a published literature procedure. Thus, substantially in accordance with the step of a Curtius rearrangement, the acid chloride of Formula 2 is reacted with sodium azide in acetone to yield the azide compound of Formula S. The azide of Formula 6 is heated in a polar high boiling solvent, such as t-butanol, to provide the intermediate isocyanate of Formula 7, which is hydrolyzed to yield a compound of Formula 2a. 
Reaction Scheme 12 illustrates examples for preparing compounds of Formula 3a where such compounds are not available commercially or by a published literature procedure. Thus, by way of example 2,5-difluoro-4-bromobenzoic acid (available by the literature procedure of Sugawara et al. Kogyo Kaguku Zasshi 1970, 73, 972-979) is first esterified by treatment with ethyl alcohol and acid to yield the corresponding ester, and thereafter is reacted with butyl lithium followed by carbon dioxide to give the monoester of 2,5-difluoro terephthalic acid (Compound T1). A similar sequence of reactions performed on 2,3,5,6-difluoro-4-bromobenzoic acid (available by the literature procedure of Reuman et al. J. Med. Chem. 15 1995, 38, 2531-2540) yields the monoester of 2,3,5,6-tetrafluoroterephthalic acid. The just illustrated sequence of reaction can be, generally speaking, utilized for the synthesis of all compounds of Formula 3a with such modification which will become readily apparent to those skilled in the art, where such compounds are not available by a known literature procedure.
Numerous other reactions suitable for preparing compounds of the invention, and for converting compounds of Formula 1 within the scope of the present invention into still further compounds of the invention, and also for preparing the reagents of Formula 2. Formula 3. Formula 2a and Formula 3a will become readily apparent to those skilled in the art in light of the present disclosure. In this regard the following general synthetic methodology, applicable for conversion of the compounds of Formula 1 into further homologs and/or derivatives, and also for preparing the reagents of Formula 2 and 3, (as well as 2a and 3a) is noted.
Carboxylic acids are typically esterified by refluxing the acid in a solution of the appropriate alcohol in the presence of an acid catalyst such as hydrogen chloride or thionyl chloride. Alternatively, the carboxylic acid can be condensed with the appropriate alcohol in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. The ester is recovered and purified by conventional means. Acetals and ketals are readily made by the method described in March, xe2x80x9cAdvanced Organic Chemistry,xe2x80x9d 2nd Edition, McGraw-Hill Book Company, p 810). Alcohols, aldehydes and ketones all may be protected by forming respectively, ethers and esters, acetals or ketals by known methods such as those described in McOmie, Plenum Publishing Press, 1973 and Protecting Groups, Ed. Greene, John Wiley and Sons, 1981.
A means for making compounds where A is (CH2)q (q is 1-5) is to subject the compounds of Formula 1, where B is an acid or other function, to homologation, using the well known Arndt-Eistert method of homologation, or other known homologation procedures. Similar homologations (and several of the other herein mentioned synthetic transformations) can be transformed on the reagent of Formula 3. Compounds of the invention, where A is an alkenyl group having one or more double bonds can be made, for example, by having the requisite number of double bonds incorporated into the reagent of Formula 3. Generally speaking, such compounds where A is an unsaturated carbon chain can be obtained by synthetic schemes well known to the practicing organic chemist; for example by Wittig and like reactions, or by introduction of a double bond by elimination of halogen from an alpha-halo-carboxylic acid, ester or like carboxaldehyde. Compounds of the invention where the A group has a triple (acetylenic) bond can be made by using the corresponding aryl or heteroaryl aldehyde intermediate. Such intermediate can be obtained by reactions well known in the art, for example, by reaction of a corresponding methyl ketone with strong base, such as lithium diisopropyl amide. The acids and salts derived from compounds of Formula 1 are readily obtainable from the corresponding esters. Basic saponification with an alkali metal base will provide the acid. For example, an ester of Formula 1 may be dissolved in a polar solvent such as an alkanol, preferably under an inert atmosphere at room temperature, with about a three molar excess of base, for example, potassium or lithium hydroxide. The solution is stirred for an extended period of time, between 15 and 20 hours, cooled, acidified and the hydrolysate recovered by conventional means.
The amide (in Formula 1 B is CONR9R10) may be formed by any appropriate amidation means known in the art from the corresponding esters or carboxylic acids. One way to prepare such compounds is to convert an acid to an acid chloride and then treat that compound with ammonium hydroxide or an appropriate amine.
Alcohols are made by converting the corresponding acids to the acid chloride with thionyl chloride or other means (J. March, xe2x80x9cAdvanced Organic Chemistryxe2x80x9d, 30 2nd Edition, McGraw-Hill Book Company), then reducing the acid chloride with sodium borohydride (March, Ibid, pg. 1124), which gives the corresponding alcohols.
Alternatively, esters may be reduced with lithium aluminum hydride at reduced temperatures. Alkylating these alcohols with appropriate alky halides under Williamson reaction conditions (March, Ibid, pg. 357) gives the corresponding ethers. These alcohols can be converted to esters by reacting them with appropriate acids in the presence of acid catalysts or dicyclohexylcarbodiimide and dimethylaminopyridine.
Aldehydes can be prepared from the corresponding primary alcohols using mild oxidizing agents such as pyridinium dichromate in methylene chloride (Corey, E. J., Schmidt, G., Tet. Lett., 399, 1979), or dimethyl sulfoxide/oxalyl chloride in methylene chloride (Omura, K., Swern, D., Tetrahedron. 1978. 34, 1651).
Ketones can be prepared from an appropriate aldehyde by treating the aldehyde with an alkyl Grignard reagent or similar reagent followed by oxidation.
Acetals or ketals can be prepared from the corresponding aldehyde or ketone by the method described in March, Ibid, p 810.
Compounds of Formula 1 where B is H can be prepared from the corresponding halogenated aromatic compounds, preferably where the halogen is I.